Japanese Unexamined Patent Application Publication No. 10-105895 and Japanese Unexamined Patent Application Publication No. 11-345393 describe automatic driving systems that perform acceleration and deceleration control in order to facilitate merging when plural traffic lanes (lanes) merge ([0027] to [0034] in Japanese Unexamined Patent Application Publication No. 10-105895, and the abstract, [0004], [0005], [0010], [0811], [0032] in Japanese Unexamined Patent Application Publication No. 11-3453935).